Just days away from contesting a parliamentary by-election in Stoke-on-Trent, Mr Nuttall is now facing calls to resign as an MEP and was branded a "coward" after a party press officer offered to take the blame over the posts.

Mr Nuttall has apologised over the claim, carried on his official website for at least six years, after he was forced to admit it was wrong during a live radio interview.

Today a message on paulnuttallmep.com said the site was offline for "scheduled maintenance".

Barry Devonside, whose son Christopher, 18, was among the victims, said the Ukip leader's credibility had "gone out of the window" and branded the post "insensitive".

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Liverpool Mayor Joe Anderson has called on the Ukip leader to 'explain himself to the people'

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Lib Dem leader Tim Farron has called Nuttall 'a coward'

"We don't need this kind of thing from Paul Nuttall. He should know better as a politician and leader of Ukip," Mr Devonside said.

Hillsborough Family Support Group chairwoman Margaret Aspinall told LBC radio: "A lot of people who were there that day did lose close personal friends and I think it's an insult to them as well as to all the families who did lose somebody on that day."

Mr Nuttall apologised on Tuesday for the claim – contained in at least two press releases on his website – after being challenged during an interview with Radio City Talk in Liverpool.

He told presenter Dave Easton: "I haven't lost a close personal friend, I've lost someone who I know. I haven't put that out, that is wrong."

Hillsborough 25 years on
Tue, April 15, 2014

The memorial service marking the 25th anniversary of the Hillsborough disaster

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MP Andy Burnham takes his seat after his speach, during the Hillsborough 25th Anniversary Memorial Service at Anfield Stadium, Liverpool

On Tuesday Ukip press officer Lynda Roughley said she was "entirely responsible" for the website post and had offered her resignation.

A Ukip spokesman said on Wednesday that the resignation had been rejected, adding: "Obviously Paul is grateful for her offer, but what sort of chap would he be to say her career is dead for what seems to be a minor error six years ago?"

In a statement Mr Nuttall made clear he stands by his account of being present at the disaster as a 12-year-old fan, after doubts were raised by the Guardian.

"From the upper tier of the Leppings Lane end of the Hillsborough Stadium, I watched the events of that day unfold with horror," he said.